We saw what happened when Skittles gave up too much of its online identity to consumers. By contrast, Coke’s handling of a recent Facebook challenge shows that it’s possible to engage customers and even offer them ownership without giving up control of the brand. What’s interesting to me is how easily it could have gone, well, flat. But, it didn’t. Today, Coke is second only to President Barack Obama in its number of Facebook fans, and, technically, it happened overnight.

The fan page that grew so explosively wasn’t a corporate page. It was started by two guys in Los Angelesand, over time, racked up a couple of million fans. Nobody’s sure why, but their page, out of over 200 dedicated to Coke, aroused an unquenchable interest among Facebook users.

Then, a move by Facebook threatened to take the fizz out of the page’s popularity. Last November, in an effort to crack down on obscene or offensive comments and spam, Facebook began to enforce its policy that any branded page must be authorized by the brand in question. It insisted that Coca-Cola either take over the page or shut it down.

Coke, on the other hand, came up with an ingenious idea. Instead of shutting down the page or banishing it to the Facebook equivalent of Siberia, it asked the creators if they’d be willing to share its administration with the company. It then flew them to Atlanta for a tour of headquarters, a few days of discussions, and a peek at the brand archives. The result? The brand page is still growing, and Coke’s “official” Facebook presence is bigger, cooler, and more authentic than it ever could have been on its own.